Any info about 500mm f/8 Sigma-XQ Mirror Ultra-Telephoto?

[GlassBreaker]

Hello.
I recently bought this metal beast from the ebay for around $60 with shipping.
But cannot find any samples. So, until I got it, I would like to know more about this lens.
Does anyone have experience with it? Any opinions?
I am going to post a review.
But considering I am from the Ukraine, it will take a couple of weeks until I will receive it.
Thanks!

[calvin83]

Welcome! ..... Never see sharp photos taken with XQ mirror 8/500 on the web. May be your copy will be OK in quality...

[GlassBreaker]

I never saw any samples from it at all. Just small descriptions on the net. I decided to take a chance for this price. It is in perfect condition with original case. You think it is a waste of money? I wonder what eXtra Quality means for Sigmas.

[calvin83]

Most XQ lens has excellent build quality but below average performance in the same era(expect some goold ones like the 1.8/135 and 2.8/55 macro). For practical use, the Tamron 8/500 mirror will be more suitable and affordable.

P.S. I have a mint XQ 4/300 sitting in my dry box and I think it worth every penny I paid for($30 without shipping).